What is better or these two dSLR?

1) Canon EOS 550d + 18mm-55mm lens.
2) Nikon D3100 + 18mm-55mm lens.
3) Canon EOS 500d + 18mm-55m lens.

I have no plans to buy a more expensive lens yet. (Meaning few years.)

Added (1). I mean of these THREE

Auto focus in video mode is the only feature that 550D don't have.

60 fps Video shooting with 550D is a amazing experience, D3100 not capable of recording 60fps video.

Both of these camera are very good, The most important factor is nikon D3100 is less expensive,

Main Features of D3100

* 14.2 megapixel DX-format CMOS sensor
* 3.0″ LCD monitor (230, 000 dots)
* Image sensor cleaning (sensor shake)
* 11 AF points (with 3D tracking)
* IS0 100-3200 range (12, 800 expanded)
* HD movies (1080, 720p or WVGA)

Main Features of Canon 550D

* 18 MP APS-C CMOS sensor
* DIGIC 4
* ISO 100-6400, H:12800
* 3.7fps shooting
* Full HD movies
* 7.7cm (3.0") 3:2 Clear View LCD with 1, 040k dots
* iFCL metering
* Quick Control screen
* Ext. Mic socket
* Movie crop

Add the Sony A33, A55, A560 and A580. The A55 and A580 have an EXCELLENT sensor.